\newproblem{lay:4_3_12}{
  % Problem identification
	\begin{large}
	  \hspace{\fill}\newline
    \textbf{Lay, 4.3.12}
	\end{large}
	\\
  \ifthenelse{\boolean{identifyAuthor}}{\textit{Carlos Oscar Sorzano, Aug. 31st, 2013} \\}{}

  % Problem statement
	Find a basis for the set of vectors in $\mathbb{R}^2$ on the line $y=-3x$.
}{
  % Solution
	All these vectors are of the form
	\begin{center}
		$\mathbf{r}=\begin{pmatrix}x\\-3x\end{pmatrix}=x\begin{pmatrix}1\\-3\end{pmatrix}$
	\end{center}
	So, a basis for these vectors is
	\begin{center}
		$B=\left\{\begin{pmatrix}1\\-3\end{pmatrix}\right\}$
	\end{center}
}
\useproblem{lay:4_3_12}
\ifthenelse{\boolean{eachProblemInOnePage}}{\newpage}{}
